Use opposite operator instead of negating the whole expression with a logic complement operator. Example:
<pre>
public boolean bar(int a, int b) {

  if (!(a == b)) // use !=
    return false;

  if (!(a < b)) // use >=
    return false;

  return true;
}
</pre>

<p>
  This rule is deprecated, use {rule:java:S1940} instead.
</p>
